Tower tool for minimally invasive surgery

ABSTRACT

A rod reduction tool assembly includes an outer tube with outer tangs for engaging a bone anchor, an inner partially tubular pin support and a threaded cap mated to the outer tube and engaging the inner pin support.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/833,899, filed Aug. 24, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/197,848, filed Mar. 5, 2014, which claims thebenefit of U.S. Provisional Patent App. Ser. No. 62/852,626, filed Mar.15, 2013, the entireties of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to apparatus and methods for use inperforming spinal surgery using minimally or less invasive techniquesand, in particular, to tools and methods of using such tools, especiallyfor reducing a rod or other longitudinal connecting member into a spinalscrew.

For many years, spinal osteosynthesis apparatuses have been utilized tocorrect spinal deformities, injuries or disease. In such procedures,substantially rigid longitudinal connecting members, for example,elongate solid rods, are surgically attached to vertebrae of the spineto provide support and/or to realign or reposition certain vertebrae.The longitudinal connecting members are typically secured to vertebraeutilizing bone screws and other spinal implants. In order to reduce theimpact of such surgery on the patient, a desirable approach is to insertsuch implants percutaneously or with surgical techniques that are lessinvasive to the body of the patient.

Problems arise when implant deployment and insertion tools designed fortraditional open surgery that is more invasive are utilized inpercutaneous or less invasive surgery. The tools may be bulky, oversizedor have irregular surfaces or protrusions that can catch and traumatizetissues. A projecting actuator arm or fastening member may be usefulwith respect to the spinal screw implantation process or the rodreduction process, but there may be insufficient clearance to use suchstructure and/or such structure may produce additional unwanted traumawhich the percutaneous surgery is attempting to avoid. A percutaneous orless invasive procedure also presents challenges in the implantation ofelongate connecting members that have historically required a longincision and open wound in order to provide for the length of theconnecting member and the space required for the surgeon's hands as wellas the tools needed to manipulate the rod. Such problems are thencompounded by the implants and insertion tools used with the connectingmember.

SUMMARY OF THE INVENTION

A tool assembly according to an embodiment of the invention includes arotate-on and rotate-off partially tubular and partially open structureproviding an open or through channel, the tool for engaging and holdinga bone anchor during surgery and particularly during reduction of a rodor other longitudinal connecting member into a receiver or head of a thebone anchor that is typically in the form of a monoaxial or polyaxialbone screw having spaced arms for receiving a rod or other longitudinalconnecting member, such screws typically identified as “open” screws.The tool assembly includes structure at a lower end thereof that isoperably mateable with outer surfaces of opposed arms of the receiver ofthe bone anchor. Furthermore the tool structure includes surfaces thatengage both inner and outer upper surface portions of each arm of thereceiver. Also, the tool structure is sized for rotating on and off ofthe receiver in either a clockwise or counterclockwise manner, even whena rod is located within the receiver.

A medical implant holding tool according to an embodiment of theinvention includes an engagement structure at a lower end thereofoperably mateable with opposed arms of an open receiver of a boneanchor, the receiver opposed arms defining a channel for receiving alongitudinal connecting member, an elongate outer holding tool with anupper tubular portion having a top surface and a first helical thread,the tubular portion terminating at a pair of opposed downwardlyextending tangs located opposite the top surface, each tang having anaperture and the engagement structure for mating with one of the arms ofthe bone anchor receiver; and a cap having a bottom surface and a secondhelical thread sized and shaped for mating engagement with the firsthelical thread of the outer holding tool, the cap bottom surfaceengageable with an elongate portion and wherein rotation of the cap withrespect to the outer holding tool moves the elongate portion downwardlyinto a location against an outer surface of the bone anchor, therebyrotationally fixing the holding tool tangs with respect to the boneanchor.

Objects of the invention include providing apparatus and methods thatare easy to use and especially adapted for the intended use thereof.Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a tool assembly according to anembodiment of the invention shown with a polyaxial bone screw, a rod (inphantom) and a closure top.

FIG. 2 is a reduced exploded front elevational view of the tool assemblyof FIG. 1 including an outer holding tool, an inner pin support, aretaining ring and a threaded cap.

FIG. 3 is an enlarged and partial perspective view of a top portion ofthe outer holding tool.

FIG. 4 is a reduced top plan view of the outer holding tool of FIG. 3.

FIG. 5 is a reduced bottom plan view of the outer holding tool of FIG.3.

FIG. 6 is an enlarged and partial perspective view of a bottom portionof the outer holding tool.

FIG. 6A is a reduced and partial cross-sectional view taken along theline 6A-6A of FIG. 6.

FIG. 7 is a reduced and partial side elevational view of the bottomportion of the tool shown in FIG. 6.

FIG. 8 is a reduced and partial front elevational view of the bottomportion of the tool of FIG. 6 and shown with portions broken away toshow the detail thereof.

FIG. 9 is an enlarged and partial perspective view of a top portion ofthe inner pin support of FIG. 2.

FIG. 10 is an enlarged and partial perspective view of one of the innerpins shown in FIG. 2.

FIG. 11 is an enlarged and partial perspective view of a portion of thebone screw shown in FIG. 1.

FIG. 12 is a reduced and partial side elevational view of the bone screwportion shown in FIG. 11.

FIG. 13 is an enlarged and partial cross-sectional view taken along theline 13-13 of FIG. 12.

FIG. 14 is an enlarged and partial perspective view of the tool assemblyand bone screw shown in FIG. 1, shown in a first stage of assembly.

FIG. 15 is a reduced and partial front elevational view of the toolassembly and bone screw as shown in FIG. 14 and with portions brokenaway to show the detail thereof.

FIG. 16 is a reduced and partial perspective view, similar to FIG. 14showing the tool assembly in a later stage of assembly with the bonescrew.

FIG. 17 is an enlarged and partial front elevational view of the toolassembly and bone screw as shown in FIG. 16 and with portions brokenaway to show the detail thereof.

FIG. 18 is another partial perspective view of the assembly of FIG. 16illustrating a top portion of the assembly.

FIG. 19 is a reduced and partial perspective view of the assembly ofFIG. 18 shown in a later stage of assembly with the bone screw shown inFIG. 16.

FIG. 20 is an enlarged and partial front elevational view with portionsbroken away of the assembly of FIG. 19 shown assembled with the bonescrew.

FIG. 21 is another partial front elevational view of the assembly ofFIG. 20 but showing different portions broken away.

FIG. 22 is a reduced perspective view of the assembly as shown in FIGS.19 to 21 and further showing a rod and a closure, the rod shown inphantom.

FIG. 23 is an enlarged and partial perspective view of the assembly ofFIG. 22 showing the rod reduced into the bone screw and the closure alsorotated into the bone screw, the rod shown in phantom.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

It is also noted that any reference to the words top, bottom, up anddown, and the like, in this application refers to the alignment shown inthe various drawings, as well as the normal connotations applied to suchtools and cooperating devices, and is not intended to restrictpositioning of the tools in actual use. It is also noted that referenceto words such as front, back, anterior and posterior used in thisapplication also refer to the alignment shown in the various drawings,and in particular, when possible, with reference to the human spine andhuman body, but also is not intended to restrict positioning of thetools in actual use.

With reference to FIGS. 1-23, the reference numeral 1 generallydesignates a tool assembly according to an embodiment of the presentinvention that may be used alone or in combination with other toolsduring various steps of a procedure of inserting two or more boneanchors 4 into vertebrae followed by the installation of a longitudinalmember, such as a rod 8 and closure members or tops 9, into the bonescrews 4 in a process according to an aspect of the present invention.The tool assembly 1 is particularly configured for reducing the rod 8down into the bone screw 4 having a dual or two start helical guide andadvancement structure thereon that mates with the two or dual-startclosure top 9. The multi-start closure top 9 that includes two flangeform structures thereon is shown and described, for example, inApplicant's U.S. patent application Ser. No. 13/694,849 filed Jan. 10,2013, the entire disclosure of which is incorporated by referenceherein. The '849 application also discloses other two-start closures,for example two-start reverse angle thread closures and two-startbuttress thread closures.

With particular reference to FIGS. 11-13, the tool assembly 1 isdesigned to cooperate with an upper surface portion 12 located on eachopposed arm 13 of a receiver 14 of the bone anchor 4. Although aparticular geometry is described herein for the bone anchor upperportion 12, it is noted that tools according to the invention andcooperating bone screw structure may take a variety of forms as long asboth inner and outer surface portions of each receiver arm is engaged bythe tool assembly. The bone anchor 4 may be polyaxial, mono-axial (onepiece, fixed) or other types of hinging or uni-planar pivot screw. Theillustrated bone anchor 4 includes a threaded shank 18 that may bearticulated (both pivoting and rotation) with respect to the receiver 14and further includes an inner open retaining ring to capture the shankin the receiver as well as a lower rod holding compression insert. Theinner mechanism for capturing the pivotable shank within the particularbone screw 4 that is partially shown in this application issubstantially similar to the assemblies described in detail in U.S.Provisional Patent Application No. 61/795,984 filed Oct. 31, 2012 andincorporated by reference herein (the disclosure of which wasincorporated into U.S. Ser. No. 14/061,393 filed Oct. 23, 2013) andtherefore will not be described in detail in this application. It isalso noted that other polyaxial bone screw shanks known in the art maybe used in lieu of the particular shank shown in the drawings that isuploaded into the receiver and captured therein by an open retainingring.

Because the tool assembly 1 may be used with many types of bone anchors,including hooks and other screw types, the illustrations primarily showonly the top portion 12 of each arm 13 of the receiver 14 which furtherincludes the following features: a substantially planar top surface 21;an upper outer cylindrical surface portion 22 having a central groove23; a lower or ledge surface 24 that has an undercut; a lowercylindrical surface portion 26; an outwardly sloping surface portion 28terminating at an outer surface 29 of the arm 13; an inner cylindricalsurface 30 located adjacent the arm top surface 20; an inner slopingsurface 32 that extends inwardly to a beginning of a helically wouldguide and advancement structure 34 that in the illustrated embodiment isa flange form; and opposed substantially planar front and back surfaces36. As stated above, the top surface 20 is planar and circular orannular. The top surface 20 is located between and adjacent to the outercylindrical surface 22 and the inner cylindrical surface 30, thesurfaces 22 and 30 are both parallel to and run coaxial with a centralaxis of the receiver 14. The vertical groove 23 formed in the surface 22is parallel to the receiver axis and is sized and shaped for slidinglyreceiving one of the support pins of the tool assembly 1 as will bedescribed in greater detail below. The lower undercut surface 24 as bestshown in FIG. 13 is adjacent to the cylindrical surface 26 and runsdownwardly and outwardly to the cylindrical surface 22, the surface 24defines an acute angle with the surface 26. The cylindrical surface 26terminates at the outwardly sloping surface 28 that is illustrated assubstantially frusto-conical. The surface 28 terminates at an outersurface 29 of the receiver arm 13 that is illustrated as having avariety of curved and planar surfaces and generally runs downwardly andparallel to the central axis of the receiver. As is shown in FIG. 23,when the rod 8 is captured within the receiver 14, the rod 8 is locatedbelow an intersection of the surface 28 and the surface 29.

Returning to the tool assembly 1 and particularly to FIGS. 1 and 2, theassembly 1 includes an outer holding tool 40, an inner pin support 42, athreaded cap 44 and associated external deformable and/or elasticretaining or compression ring 45. The holding tool 40 and inner pinsupport 42 are typically made from harder materials, but a variety ofsuitable materials are possible, for example, including but not limitedto metals, metal alloys, plastics, polymers, composites and blendsthereof. For example, the tool components may be made from stainlesssteel, titanium, polymer blends that may be carbon reinforced, such apolyetheretherketone (PEEK) and or other radiolucent or non-radiolucentmaterials. In certain embodiments the components 40 and 42 may be rigidand in other embodiments, more flexible, allowing for some flexing orbending without compromising strength of the components. When assembled,the individual components 40, 42, 44 and 45 engage one another as shownin FIG. 1 to result in a holding and guide tool as well as a rodreduction tool that forms a continuous, substantially cylindrical innerpathway from a top surface 46 of the assembled tool 1 (which is the topof the pin support 42) to the engaged bone anchor receiver 24 forreceiving tooling and the closure top 9 and or other bone anchorcomponents.

The outer holding tool 40 is elongate and includes an upper tubular andsubstantially cylindrical portion 48 extending axially from a topsurface 49 and generally terminating at an integral pair of opposeddownwardly extending prongs, tangs or arms 50, each arm having identicalopposed tooling features located near bottom surfaces 51 thereof. Thearms or tangs 50 are sized and shaped for forming a through channel fromthe bottom surfaces 51 to the tubular upper portion 48 for receiving therod 8 or other longitudinal connecting members or other tools or bonescrew components. As best shown in FIG. 1, the tubular portion 48 isrelatively short as compared to a length of the opposed tangs or arms 50that are generally sized and shaped to be sufficiently long to extendfrom an implanted bone screw 4 through an exterior of a patient's skinso as to provide an outwardly extending and upper handling portion atthe tubular portion 48 that allows and provides for gripping by asurgeon during procedures utilizing the tool assembly 1, with or withoutthe other cooperating tools, such as bone screw or closure top driversto name a few.

With particular reference to FIGS. 3, 4 and 15, the outer tool uppertubular portion 48 located at and near the substantially planar andannular top surface 49 further includes an inner substantiallycylindrical surface 54 having a pair of opposed grooves 56 sized andshaped for slidingly receiving a pair of spaced cylindrical pins 57 ofthe inner support 42. The grooves 56 extend axially along an entirelength of the tubular portion 48 and are axially aligned with throughbores of the arm portions 50 as will be described in greater detailbelow. Also formed in the surface 54 near the top surface 49 is ahelical thread 60 configured for mating under rotation with the threadedcap 44. Located and spaced below the threaded surface 60 is adiscontinuous annular seat 62 running perpendicular to and inwardly fromthe cylindrical surface 54 to an inner cylindrical surface 63. Thecylindrical surface 63 has a diameter that is the same as inner surfacesof the tangs 50. The surfaces 62 and 63 partially define a pair ofopposed inner tool support features, generally 64, that extenddownwardly to the juncture of the upper portion 48 with the elongatetangs 50. A pair of opposed planar surfaces 66 partially define atermination of the tubular structure 48 and the beginning of the spacedtangs 50 that are integral with the tubular upper structure 48. Formedin the surfaces 66 and extending through the otherwise substantiallysolid arms are through bores 68 aligned with the upper grooves 56 andsized and shaped to closely but slidingly receive the pins 57. Forexample, see FIG. 6A that illustrates the substantially solid nature ofthe arms 50 and the cylindrical form of one of the through bores 68.From the surfaces 66 to the bottom 51 of each of the tangs or arms 50,the arms have substantially cylindrical opposed inner surfaces 70 havinga diameter the same or substantially similar to the diameter of theinner surfaces 63. The arms further include outer surfaces 72 runningalong a length of each arm that are also substantially cylindrical andinclude some other surface contours. Located directly above each arm ina substantially cylindrical outer surface 74 of the upper portion 48that is contiguous with the arm outer surfaces 72 are a pair of opposedthrough apertures 76. The apertures 76 provide a window for viewing anindicator printed or stamped on the inner pin support 42 to inform theuser whether or not the pins 57 are engaged with the bone screw receiver14 as will be described in greater detail below.

Moving to a lower portion of each of the arms, at a locationapproximately two-thirds to three-fourths along a length of the tangs50, a pair of opposed discontinuous helically wound square threads 80are formed on each arm inner cylindrical surfaces 70. In the illustratedembodiment, the opposing square thread forms 80 are identical as theyare configured for mating with the particular guide and advancementstructure 34 of the illustrated bone screw receiver 14 that is a dual ortwo-start flange form structure. It is noted that the tool inner armscould be equipped with mating flange form structure. However, such isnot necessary, as the square thread form 80 is sized and shaped tohelically receive the flange forms on the mating closure top 9 and,unlike the flange form structure on the receiver arms, the closure top 9does not need to frictionally fix upon anything within the tool assembly1. Therefore, the square thread forms 80 are a more cost effectiveoption. It is noted that the thread forms 80 may be reconfigured forrotatingly receiving and mating with closure tops having differentthread-like or non-threadlike helically guide and advancement structuresthereon. The assembly 1 advantageously cooperates with dual threadforms, allowing for rotate-on and off of the assembly 1 in either aclockwise or counterclockwise manner as both sides of the cooperatingreceiver guide and advancement structure are identical for cooperatingwith the dual-form closure 9. The thread forms 80 terminate at a lowerimplant engaging portion, generally 82, located near the bottom surfaces51.

With particular reference to FIGS. 5-8 and 15-17 and FIG. 21, the lowestor bottom of each of the thread forms 80 has a bottom surface 86 thatextends radially outwardly to a cylindrical surface portion 88 that isthe same as or has a same diameter as the inner cylindrical surface 70running along the tangs 50 above the square thread forms 80 and up tothe tubular upper portion 48. The surface portion 88 terminates at abottom substantially planar and partially annular surface 90. Thesurface 90 slopes downwardly and radially outwardly from the cylindricalsurface 88 and is sized and oriented to engage and fit closely againstthe sloping surface 32 of the receiver upper portion 12 that is adjacentthe receiver guide and advancement structure 34. Extending upwardly fromthe tool surface 90 is a cylindrical surface 91 that partially defines acut-out or recess, generally 93 that is formed into each tang bottom 51and generally beneath each of the square thread structures 80. As can beseen in FIGS. 8 and 20, for example, each recess 93 extends from thethread form structures 80 generally outwardly toward the arm outersurface 72 a distance that is almost half a diameter of the through bore68 that receives the pins 57. Additional surfaces that define the recess93 are a top or ceiling surface 94, an outer concave cylindrical surface95, a sloped surface 96, a lower cylindrical surface 97 and a lowersloped surface 98 that terminates at or near the tang bottom surface 51.The surface 94 is sized and shaped to closely engage the receiver topsurface 20. The outer concave cylindrical surface 95 is sized and shapedto closely engage the outer convex cylindrical surface 22 of thereceiver. The sloped surface 96 that slopes downwardly and outwardlytoward the surface 95 is sized and shaped to closely receive the slopedsurface or undercut 24 of the receiver. The lower concave cylindricalsurface 97 is sized and shaped to closely receive the lower convexcylindrical surface 26 of the receiver. Finally, the downwardly andoutwardly extending surface 98 is sized and shaped to closely receivethe surface 28 of the receiver upper portion 12.

With particular reference to FIGS. 2, 9, 10 and 15, the inner pinsupport 42 includes an upper tubular portion 102 located near the topsurface 46 that is opposite bottom arm end surfaces 103. The uppertubular portion includes an inner cylindrical surface 104 coaxial withan outer cylindrical surface 105. Portions of the inner cylindricalsurface 104 extend from the top surface 46 to the arm bottom surfaces103. An annular recess 106 located near the top surface 46 and formed inthe outer surface 105 is sized and shaped for receiving a portion of theretainer ring 45. The outer cylindrical surface 105 extends from therecess 106 to an annular step 107 perpendicular to the surface 105 andextending radially outwardly therefrom. The annular step 107 terminatesat an outer cylindrical surface 108, portions of which extend to thebottom arm surfaces 103. Below and near the step 107, a cut-out,generally 109 separates the tubular portion defined by the outer surface108 and the inner surface 104 into two opposed arms 111 that terminateat respective bottom surfaces 103. Each arm 111 is fixed to one of theelongate pins 57 near top surfaces 116 thereof. Although the illustratedembodiment shows a fixing between the arm 111 outer surfaces 108 andcylindrical surfaces 118 of the pins 57, such as welding, it is notedthat each arm 111 may also be integral with the respective adjacent pin57. Each pin outer surface 118 terminates at a radially inwardlyextending ledge 120. A lower pin portion extends downwardly from eachledge and terminates at a bottom surface 122. The lower pin portion isdefined in part by a cylindrical surface 124 having a diameter smallerthan a diameter of the pin portion 118. A frusto-conical surface 124that tapers radially inwardly spans between the surface 124 and thebottom 122 that is substantially planar.

The cap 44 as best shown in FIGS. 2 and 15 is tubular and includes anannular top surface 130 and an annular bottom surface 132, the top andbottom surfaces being substantially planar and perpendicular to acentral axis of the cap 44. An inner cylindrical surface 134 runs fromthe top surface 130 to the bottom surface 132. The surface 134 is sizedand shaped to slidingly fit over the cylindrical surface 105 of theinner pin support 42. The cap 44 is also sized such that the bottomsurface 132 abuts against the surface 107 of the pin support 42 and thetop surface 130 abuts against the retainer ring 106. In outer profile,the cap 44 includes a variety of cylindrical surfaces. An uppercylindrical surface 136 located adjacent to the top surface 130 includesa plurality of vertical grooves 138 to aid in handling the tool assembly1. It is noted that the surface 136 may be smooth or include othergrooves, contours, surface treatment to aid in handling of the tool 1.The surface 136 terminates at a radially outwardly extending step 140perpendicular to the surface 136. The step 140 terminates at anothercylindrical surface 142 having a diameter greater than a diameter of thesurface 136. The surface 142 terminates at a lower annular ledge surface144 that is perpendicular to the surface 142 and extends radiallyinwardly therefrom. The ledge 144 terminates at another cylindricalsurface 145 having a diameter smaller than the diameter of the surface142 and smaller than the diameter of the surface 144. The cylindricalsurface 145 is narrow and terminates at a helically wound thread 146sized and shaped to mate under rotation with the helical inner thread 60of the outer holding tool 40. For example, with reference to FIGS. 18and 19, when the pins 57 of the inner pin support 42 are located abovethe bone screw receiver 14 opposed arms 13 and thus the tool assembly 1is not fully engaged with the receiver 14, the cap annular surface orlower ledge 144 is spaced from the top surface 49 of the holding tool40. As can be seen in FIG. 18, at that time, the threaded portion 146 ofthe cap 44 is not fully mated with the inner threaded portion 60 of theouter holding tool 40. Also, such unlocked position is indicated by thepin surface “unlocked” indicator 113 as viewed through the aperture 76of the holding tool 40. With reference to FIG. 19, when the pins 57 areengaged and located in the grooves 23 of the receiver arms 13, the capannular surface or lower ledge 144 abuts against the top surface 49 ofthe outer holding tool 40. At that time, the “locked” indicator 112 isvisible through the aperture 76.

With further reference to FIGS. 2 and 15, the tool components 40, 42, 44and 45 are typically assembled prior to use and are only dissembled forcleaning purposes. As is indicated by the drawings, the inner pinsupport 42 pins 57 are slidingly received by the grooves 56 of the uppertubular portion 48 and the through bores 68 of the tangs 50 and the pinsupport body 42 is slidingly received within the outer holding toolinner cylindrical surface 54. The cap 44 inner cylindrical surface 134slides over the inner pin support 42 outer surface 105 and the cap isinitially rotated with respect to the outer holding tool 40, mating thehelical threaded portions 146 and 60 to an extent to bring the pinbottom surfaces 122 to a location generally above the attachmentportions 82. With reference to FIG. 15, at this time the outer retainingring 45 is secured in the annular recess 106 of the inner pin support 42and against the cap top surface 130.

With reference to FIGS. 14 and 15, the tool assembly 1 is now ready foruse with the upper portion 12 of the receiver arms 13. The tool assembly1 is initially positioned with the tangs 50 lowered to a locationbetween the receiver arms 13 as shown in FIG. 14, the tang surfaces 94located above the receiver arm surfaces 20. Then the assembly 1 isrotated about the receiver central axis either clockwise orcounterclockwise as desired by the user, the surfaces defining thereceiver attachment portion 82 of each tang 50 slidingly receiving theupper surfaces of each of the receiver arms 13 as previously describedherein with respect to FIGS. 16, 17 and 21. With reference to FIG. 18,at this time, the tangs 50 are not locked into place with respect to thearms as the guide pins 57 are still located above the receiver arm topsurfaces 20 as shown in FIG. 17. This unlocked position is indicated bythe indicator 113. The cap 44 is then rotated with respect to the outerholding tool 40 until the surface 144 abuts with the surface 49, atwhich time the pins 57 have been moved into a desired downward positionin the receiver grooves 23, blocking any further axial rotation betweenthe tangs 50 and the receiver arms 13. The cylindrical surface 124 isnow fully received by the groove surface 23 of each receiver arm 13. Theuser now sees the “locked” indicator 112 through the tool aperture 76 asshown in FIG. 19. With further reference to FIGS. 22 and 23, as well asto FIG. 21, at this time the dual start closure 9 may be used to reducethe rod 8 down into the receiver 14. As the closure is rotateddownwardly, splay of the tool assembly 1 tangs 50 as well as splay ofthe receiver arms 13 (both outward and inward) is controlled by the toolsurfaces 91 pressing outwardly (see arrow X in FIG. 21) against thereceiver inner cylindrical surfaces 30 as well as the tool tangs 50surfaces 96 pulling upwardly (see arrow Y in FIG. 21) and against theundercut surface 24 of each of the receiver arms. The upward force Ystabilizes the tool surface 95 and thus guards against excessive outwardsplay. The opposing tool surfaces 91 and 95 desirably capture orsandwich the receiver top portion located near the top surface 20.

With reference to FIG. 23, once the closure 9 is fully received withinthe arms of receiver 14 and fixed against the rod 8 within the receiver,the tool may be removed by rotating the cap 14 relative to the outertool portion 40 until the pins 57 are lifted away from the receiver topsurface 20 as shown in FIGS. 17 and 18. The tool assembly 1 may then berotated axially either clockwise or counterclockwise back to theposition shown in FIG. 14 and then moved upwardly away from the receiver14. As shown in FIG. 23, the tool assembly 1 is sized such that the tangbottom surfaces 51 are located above the rod 8 top surface, and thus therod 8 does not impede or prohibit rotation of the assembly 1 in eitherdirection.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed and desired to be secured by Letters Patent is asfollows:
 1. In a medical implant holding tool having engagementstructure at a lower end thereof operably mateable with opposed arms ofan open receiver of a bone anchor, the receiver opposed arms defining achannel for receiving a longitudinal connecting member, the improvementcomprising: a) an elongate outer holding tool with an upper tubularportion having a top surface and a first helical thread, the tubularportion terminating at a pair of opposed downwardly extending tangslocated opposite the top surface, each tang having an aperture and theengagement structure for mating with one of the arms of the bone anchorreceiver; and b) a cap having a bottom surface and a second helicalthread sized and shaped for mating engagement with the first helicalthread of the outer holding tool, the cap bottom surface engageable withan elongate portion and wherein rotation of the cap with respect to theouter holding tool moves the elongate portion downwardly into a locationagainst an outer surface of the bone anchor, thereby rotationally fixingthe holding tool tangs with respect to the bone anchor.
 2. Theimprovement of claim 1, wherein the pin support upper portion has acylindrical outer surface portion and the cap is slidingly receivedthereon.
 3. The improvement of claim 2, further comprising a deformablering partially located in an annular recess formed in the cylindricalsurface portion, the deformable ring located above the cap.
 4. Theimprovement of claim 1, wherein the tang apertures are in the form ofaxial through bores.
 5. The improvement of claim 1, wherein the outerholding tool tubular portion is integral with the downwardly extendingtangs.
 6. The improvement of claim 1, wherein the inner pin supportupper portion is fixed to the pair of opposed elongate pins.
 7. Theimprovement of claim 1, wherein each tang has a first surface and anopposed second surface, the first surface sized and shaped for engagingan inner curved surface of a receiver arm and the second surface sizedand shaped for engaging an outer curved surface of the receiver arm, thefirst and second tangs rotatably mounted on and off of the receiver armsurfaces.
 8. The improvement of claim 1, further comprising an inner pinsupport received within the outer holding tool, the pin support havingan upper portion connected to a pair of opposed elongate pins, each pinsized and shaped to extend through the aperture of one of the outerholding tool tangs.
 9. In a combination of a bone attachment structurehaving a receiver and a medical implant holding tool having receiverattachment structure at a lower end thereof operably mateable with thereceiver; the improvement wherein: a) the receiver has two arms, eacharm having an undercut first surface projecting downwardly toward abottom thereof and a curved surface located directly above the undercutsurface; and b) the tool has an outer portion, an inner portion slidablyreceived within the outer portion and a cap, the outer portion havingstructure in engagement with the receiver undercut surface, the innerportion having a pair of opposed pins, each pin extending through anaperture of the outer portion, the cap threadably connected to the outerportion and in abutment with the inner portion, and wherein rotation ofthe cap with respect to the outer portion causes the cap to pressagainst and move the inner portion in a downward direction toward thereceiver and thereby move the pair of opposed pins into engagement withthe receiver arm curved surfaces.
 10. The improvement of claim 9,wherein each receiver arm has an inner surface located directly above adual start guide and advancement structure and wherein the tool engagesthe inner surface.
 11. The improvement of claim 10, wherein the tool isrotatable on and off of the receiver in both a clockwise and acounterclockwise manner.
 12. In a medical implant holding tool havingengagement structure at a lower end thereof operably mateable withopposed arms of an open receiver of a bone anchor, the receiver opposedarms defining a channel for receiving a longitudinal connecting member,the improvement comprising: a) an elongate outer holding tool with atubular portion having a top surface and an inner cylindrical surfacehaving a first helical thread, the tubular portion terminating at a pairof opposed downwardly extending tangs located opposite the top surface,each tang having an aperture and the engagement structure for matingwith one of the arms of the bone anchor receiver; b) an inner pinsupport received within the outer holding tool, the pin support havingan upper portion connected to a pair of opposed elongate pins, each pinsized and shaped to extend through the aperture of one of the outerholding tool tangs; and c) a cap having a bottom surface and a secondhelical thread sized and shaped for mating engagement with the firsthelical thread of the outer holding tool, the cap bottom surfaceengageable with the inner pin support upper portion and wherein rotationof the cap with respect to the outer holding tool moves the pinsdownwardly into a location against an outer surface of the bone anchor,thereby rotationally fixing the holding tool tangs with respect to thebone anchor.